(a) Field of the Invention
The present invention relates to a cellulose-based filament for a tire cord, a bundle including the same, a twisted yarn including the same, and a tire cord including the same. More particularly, the present invention relates to a filament for a tire cord showing less stress by twisting and superior mechanical properties, a bundle including the same, a twisted yarn including the same, and a tire cord including the same.
(b) Description of the Related Art
Tire cords are used as a framework constituting a tire, and polyester, nylon, rayon, aramid, steel, etc., are used as materials for tire cords.
During driving, tires are exposed to high temperatures due to friction, and at the same time, they must endure the weight of the car. The properties of the tires depend on the properties of the tire cord constituting a framework of the tire.
Therefore, the tire cord needs basic properties such as high tenacity and initial modulus, superior heat resistance, superior fatigue resistance and form stability, and good adhesiveness to rubber of the tire.
Recently, use of a tire cord has been determined by the inherent properties thereof, because most of the well-known tire cords satisfy some of the above properties but do not satisfy all of the properties at the same time.
Generally, tire cords are prepared by processes of preparing a cord yarn by twisting filament fibers together, dipping the same in an adhesive solution, and heat-treating the same to prepare a single cord.
Single cords are then formed into a cord fabric by a weaving process, but the properties of the filament fibers, that is, the starting materials of the cords, tend to deteriorate as the process proceeds.
As an example, according to Korean Patent Publication No. 2004-0057550, when a tire cord is prepared by twisting and dipping lyocell fibers having initial tenacity of 7.5 g/d, the tenacity was deteriorated to 4.99 g/d, which is 33% lower than the initial tenacity of the lyocell fibers. Although this result is different according to the kind of filament fiber, it is a general tendency in a tire cord.